The present invention relates generally to spacecraft deployable structures and more particularly to a boom architecture that can be flattened and furled and has a large cross-section inertia.
The subject booms have a deployed configuration where they are used as beam-like structural elements to carry bending and column loads. Boom bending stiffness characterizes this configuration and increases with increasing structural depth (cross section diameter), material thickness and material stiffness. These booms also have a furled (packaged) configuration characterized by roll diameter and height. Prior booms related to the current invention include the Storable Tubular Extendable Member (STEM) shown in FIG. 1A and the lenticular boom, which is sometimes referred to as the Collapsible Tubular Mast (CTM) shown in FIG. 1B. These booms can be stowed around a circular hub where they transition from a flattened configuration to a structurally deeper deployed shape. The STEM is composed of a single strip that, in the deployed state, curls to form a circular cross-section. Although this configuration is simple to fabricate and package, it results in a tall packaged height relative to the deployed boom diameter. Additionally, large strains are required to furl the boom. The lenticular boom is made from a pair of symmetric bell shaped halves bonded at the edges. It flattens similar to a STEM, but for the same deployed diameter, has half the packaged height as the STEM and requires less strain to flatten.
One embodiment of the current invention, the Triangular Rollable and Collapsible (TRAC) boom shown in FIG. 1C, achieves greater deployed structural depth and due to its smaller flattening strains, allows thicker materials than previous booms. These features combine to allow the fabrication of a much stiffer deployable boom with shorter packaged height.